MCP Directory

How to add JMAP MCP Server to Claude Desktop

MCP server for interacting with JMAP email servers (FastMail, Stalwart, Cyrus, James) — search, read, send, and manage email. Paste the config into ~/Library/Application Support/Claude/claude_desktop_config.json and restart Claude Desktop.

Last updated June 14, 2026 · 172★ · stdio · apikey

Claude Desktop config for JMAP MCP Server

deno run --allow-net=api.fastmail.com --allow-env=JMAP_SESSION_URL,JMAP_BEARER_TOKEN,JMAP_ACCOUNT_ID jsr:@wyattjoh/jmap-mcp@0.6.4
{
  "mcpServers": {
    "jmap-mcp-server": {
      "command": "deno",
      "args": [
        "run",
        "--allow-net=api.fastmail.com",
        "--allow-env=JMAP_SESSION_URL,JMAP_BEARER_TOKEN,JMAP_ACCOUNT_ID",
        "jsr:@wyattjoh/jmap-mcp@0.6.4"
      ],
      "env": {
        "JMAP_SESSION_URL": "https://api.fastmail.com/jmap/session",
        "JMAP_BEARER_TOKEN": "YOUR_API_TOKEN"
      }
    }
  }
}

Setup steps

  1. 1Open Claude Desktop → Settings → Developer → Edit Config (this opens ~/Library/Application Support/Claude/claude_desktop_config.json).
  2. 2Paste the JMAP MCP Server config below under the top-level "mcpServers" key.
  3. 3Fill in any placeholder secrets (API keys, paths) in the snippet.
  4. 4Save the file, then fully quit and reopen Claude Desktop.
  5. 5Open a chat and confirm JMAP MCP Server's tools appear under the 🔌 tools menu.

Before you start

  • Deno v1.40 or later
  • A JMAP-compliant email server (e.g., Cyrus IMAP, Stalwart Mail Server, FastMail, Apache James)
  • Valid JMAP authentication credentials (bearer token)

What JMAP MCP Server can do in Claude Desktop

get_mailboxes

List mailboxes/folders with their IDs, names, and metadata. Call this first to get mailbox IDs needed by search_emails (inMailbox) and move_emails (mailboxId). Supports parentId, limit (1-200, default 100), and position pagination.

search_emails

Search emails with filters (query, body, from, to, subject, inMailbox, hasKeyword, notKeyword, thread-keyword filters, before/after dates), all AND'd together. Returns email IDs plus a queryState for incremental sync. Supports limit (1-100, default 50) and position pagination.

get_emails

Retrieve specific emails by their IDs (1-50). Use the properties parameter to request only needed fields; include bodyValues plus textBody/htmlBody to get body content.

get_threads

Get email threads (conversation chains) by their IDs (1-20). Thread IDs come from the threadId property of get_emails responses. Returns email IDs per thread.

get_email_changes

Get IDs of emails created, updated, or destroyed since a previous state (state-based delta tracking). Supports maxChanges (1-500), optional fetchEmails to auto-fetch details, and properties selection.

get_search_updates

Get additions/removals within a previous search query since its queryState. Must use the same filter parameters as the original search_emails call. Supports maxChanges (1-500).

mark_emails

Mark emails (1-100 IDs) as read/unread (seen) or flagged/unflagged.

move_emails

Move emails (1-100 IDs) to a different mailbox specified by mailboxId (obtained from get_mailboxes).

Security

Authentication uses a JMAP bearer token supplied via the JMAP_BEARER_TOKEN environment variable; do not commit it. All input is validated using Zod schemas and no secrets are logged or exposed in responses. The Deno --allow-net flag should be scoped to your JMAP server's hostname (defaults to api.fastmail.com). The delete_emails tool permanently deletes email and cannot be undone — prefer move_emails to Trash for recoverable deletion.

JMAP MCP Server + Claude Desktop FAQ

Where is the Claude Desktop config file?

Claude Desktop reads MCP servers from ~/Library/Application Support/Claude/claude_desktop_config.json. Paste the JMAP MCP Server config there under the "mcpServers" key and restart the client.

Is JMAP MCP Server safe to use with Claude Desktop?

Authentication uses a JMAP bearer token supplied via the JMAP_BEARER_TOKEN environment variable; do not commit it. All input is validated using Zod schemas and no secrets are logged or exposed in responses. The Deno --allow-net flag should be scoped to your JMAP server's hostname (defaults to api.fastmail.com). The delete_emails tool permanently deletes email and cannot be undone — prefer move_emails to Trash for recoverable deletion.

Which email servers are supported?

Any JMAP-compliant server, including Cyrus IMAP 3.0+, Stalwart Mail Server, FastMail (commercial), and Apache James with JMAP support.

How do I authenticate?

Set JMAP_SESSION_URL to your server's JMAP session URL and JMAP_BEARER_TOKEN to a bearer token. JMAP_ACCOUNT_ID is optional and auto-detected if not provided.

How do I use it with a non-FastMail server?

Replace api.fastmail.com in the Deno --allow-net flag with your JMAP server's hostname, and set JMAP_SESSION_URL accordingly.

View repo Full JMAP MCP Server page